The invention relates to a strap clamping device comprising a clamping strap forming an outer loop to wrap around one or several workpieces, and a tightening device for tightening the outer loop to clamp the workpiece or workpieces.
Such strap clamping devices serve to clamp a clamping strap extending around workpieces of very different shapes.
Such strap clamping devices are particularly well suited for holding together irregularly shaped parts or parts with interrupted circumferential surfaces such as, for example, chair backs or chair legs. Irregularly shaped parts also include columns, kidney-shaped furniture or oval workpieces.
Ordinary frames of square, hexagonal or octagonal shape can also be clamped with such strap clamping devices.
With such strap clamping devices it is particularly advantageous, for better and gentler clamping of workpieces with corners, to additionally use corner elements--also referred to as clamping corners--in the region of the corners.
Strap clamping devices are known in a wide range of structural designs.
For example, strap clamping devices are known in which a lashing strap with strap ratchet is used. Other embodiments of strap clamping devices use a spindle with spindle nut for actuating the strap guide. However, in these solutions it is necessary to fix the two strap sides or strap ends firmly, and the holding of the strap during the clamping depends on how good the fixing is.
When textile straps are used as clamping straps, their large stretching is disadvantageous and is particularly noticeable when the loop has large dimensions. For this reason, metal straps are also used with strap clamping devices, but these have the disadvantage that they are awkward to handle and snap open.
In a strap clamping device design known from EP-0 302 806, the tightening device is designed so as to pull at both ends of the outer loop, and the textile strap used as clamping strap is wound onto two rolls during the clamping. However, this solution has the disadvantage that owing to the different circumferential dimensions during the winding of the clamping strap onto the rolls, uneven pulling occurs at the two sides of the outer loop.
Furthermore, the operating of the tightening device via a single turning knob which has different functions in several positions is disadvantageous. One position is for pulling out the clamping strap freely, another for winding up the clamping strap quickly, and a third position for clamping the clamping strap in narrow detent positions.
The object underlying the invention is, therefore, to so improve a strap clamping device of the generic kind that it is operable as conveniently as possible.